Diabetes is a relatively common affliction in which a person's body does not produce or properly use the hormone called insulin that is needed to convert sugar, starches and other food into energy. By some estimates, about seven percent of the population of the United States has diabetes. The symptoms of diabetes are often not recognized, and it is estimated that about one-third of people with the disease do not realize they have it.
Compared to the general population, diabetes is estimated to be even more common within the population of patients who have an implanted cardiac rhythm management device. In one estimate, approximately 11-13% of patients with implantable pacemakers have diabetes, approximately 30-38% of patients having implantable cardioverter defibrillators have diabetes, and approximately 39-45% of patients having cardiac resynchronization therapy (CRT) devices have diabetes.
It is important that diabetic patients monitor their blood sugars (i.e., glucose). Because diabetes prevents the patient's body from naturally regulating blood sugars, the diabetic patient must administer insulin in response to blood sugar levels. Failure to closely monitor blood sugars can result in dangerous conditions of hypoglycemia (blood sugar level too low) or hyperglycemia (blood sugar level too high).
Hypoglycemia is where the patient's blood glucose level is too low. Hypoglycemia can result in unpleasant symptoms, such as dizziness or shakiness, and in severe cases, can result in dangerous symptoms such as loss of consciousness, brain damage, or death. These symptoms generally result from insufficient glucose in the blood stream to the brain, thereby diminishing the brain's function. Hypoglycemia can result from excessive insulin injection. Insulin affects the ability of the body's cells to use and consume glucose, such that insulin injections can cause the cells to use too much glucose from the blood stream too quickly, resulting in a deficiency.
Hyperglycemia is where the patient's blood glucose level is too high. Sustained high blood glucose levels can cause damage to the blood vessels and to the organs. Shorter term symptoms of hyperglycemia can result in frequent thirst, hunger, and urination, as well as fatigue, weight loss, and other symptoms. Acute hyperglycemia can result in ketoacidosis, which is where the patient's liver breaks down fats and proteins in response to a perceived need for more glucose in the bloodstream. However, the problem in a diabetic patient is generally that the patient lacks the insulin needed to use glucose, not that the blood glucose level is too low. However, the body's response is to resort to drastic measures to increase the blood glucose level, and in doing so, the patient's blood glucose level becomes elevated above a desired range.
Managing diabetes is largely about managing blood glucose levels. However, continuous testing of blood glucose levels is difficult. Most patients use a finger prick type blood glucose meter that draws a small sample of blood and analyzes it for glucose content. However, this requires patient involvement and is inconvenient and unpleasant for the patient. In some cases, the patient's compliance with the testing protocol is poor. Implantable blood glucose sensors are in development that could be used to continuously monitor blood glucose levels, however, despite extensive research and development efforts, the long-term functionality of these sensors is poor.
Improved techniques are needed for monitoring blood glucose levels of a patient.